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Basic suspension setup

Discussion in 'Technical and Troubleshooting Torque' started by Roarin, Jul 10, 2006.

  1. After reading heaps of questions regarding suspension setup I thought it might be time to write a bit of a generic guide to setting up ones bike.

    First up -I am no "expert" or "professional" suspension guru. Just someone who has read & experimented heaps over the years & learnt what works for me (and a few mates willing to listen & experiment)

    Second -don't be scared of trying things for yourself. There is no "magic" or "black art" to suspension tuning. Just a few basic principles. All the suspension does is absorb bumps in the road, allowing the tyre to keep providing traction.

    Righty oh then. Where to start. Preload. Setting the "sag" The first thing to do is find yourself a helper. Chief measurer. Scribe. Whatever tickles you. Then jack the bike up from the frame, allowing the suspension to extend to its maximum length. Measure from the axle to a fixed point on the frame. Front & rear. Write these measurements down.
    Now sit the bike back down on the ground. Bounce it up & down a couple of times. Now measure again. Compare with the fully extended lengths. This should be no more than 10% of the TOTAL amount of suspension travel available. If way outside this range then you adjust the preload settings to suit.

    Next -park your fat carcase upon said bike. Put your feet on the pegs. Bounce the bike up & down a couple of times. Do this close to a wall or post so you can hold yourself & said bike upright without taking your weight off the bike. Use your elbow to hold yourself upright. Or your hand. One finger is even sufficient if you get it right. Get your helper to measure again. From the axle to the same fixed point on the frame. Write these measurements down. Compare with the origional fully extended measurements. This figure should be about 1/3 of your bikes TOTAL suspension travel. If heaps less, your spring rates are too hard. If heaps more, too soft. There is no cheap & cheerfull fix here. New springs are in order. Adding preload is not going to help you. Sorry.

    Once you have this correct, the fun bit begins. Damping. Compression & rebound. One, both, or neither depending on your bike. Set them to the standard settings. Now go find a bumpy corner. One you can take at about the fastest you reckon you will be riding at. No use setting up your bike for a pace you won't ever ride at. Or where it doesn't really matter. I would err on the side of faster rather than slower. This is where you will pick the real differences, where damping becomes more noticable -at speed.
    Now blast around said corner. At speed. How does your bike react over the bumps? Do the wheels deflect & skitter harshly over the bumps? Probably too much compression damping. Does the bike pitch & wallow fore & aft like a ship at sea? Not enough rebound damping. DON'T FIDDLE WITH THE PRELOAD. THIS WON'T FIX IT. You have already set it to suit your weight. Right back at the start of this exercise.
    Now hit the brakes (once you are round the corner of course) Does the bike try to rub its nose on the road? If it does then try adding a bit more compression damping. Once again, DON'T FIDDLE WITH THE SPRING PRELOAD. THIS WON'T FIX IT. As stated above.
    Now accelerate hard. Preferably in the lower gears. Does the bike want to squat & drag its butt along the ground like a dog with an itchy @rse? Add a bit more compression damping.
    Now blast over a series of bumps. Does the bike comfortably soak up the first couple & then start to feel harsh & deflect off the rest? If so, take out a bit of rebound damping. Does it begin to pitch & wallow? Add a bit more rebound. And so on.
    A couple of pointers. Only adjust one thing at a time. That way you will know exactly what is working for you. Or not.
    How many clicks to adjust at a time? If your damping has 20+ clicks from soft to hard, I can guarantee you will not be able to feel 1 click either way. Unless your name is Rossi. So go 4 or 5 clicks at at time. This will give you an idea of where you want to go. Then refine it from there. A couple of clicks each way to fine tune things.
    However -if you only have 4 positions, then you most likely will be able to feel the change one click makes.
    And once more, once you have set the suspension sag (unloaded to loaded), don't fiddle with it any more. The damping does the rest.
    • Like Like x 2
  2. Thanks for the tips Roarin... i'm pretty sure my suspension needs a bit of work. In the dry it hangs on like you wouldn't believe but given one drop of water or an imperfect road surface and the rear just lets it all hang out.

    Bookmarked. Thats the most thorough guide i've come across.

    Just spent the last while reading through that entire guide. Unfortunately my FZR doesnt have any front end adjustable damping so it limits my range there... but i'm pretty positive i've got a bit of setting up to do.
  3. Koma, all is not lost. There is adjustment available in non adjustable forks. It just takes time & a bit of effort.
    To adjust preload -simply make up spacers to sit on top of the fork springs. All sorts of things can be used for this purpose. Everything from washers, exhaust tubing through to bits of nylon round bar. Lots of people will disagree with this. But all one has to do is look inside any set of conventional forks & what does one find? Preload spacers. From factory. Which happen to look suspiciously like short lengths of exhaust tubing. To my eyes anyway. As long as the unloaded to loaded sags are within the specified range (up to 10% unloaded to 25-30% loaded) then all will be well. Adjust to your hearts content.
    Raising the oil level in the forks can also help. This will help reduce bottoming & give the effect of increasing compression damping near the end of the forks travel. Measuring down from the top of the legs to the oil level (with the forks compressed) is the most accurate way of doing this when adding oil.
    To adjust damping rates, one can simply try different weight or viscosity oils. However, this will change both compression & rebound damping rates if no external adjustments are available. If no satisfaction can be gained from this method then it's time to pull the dampers or cartridges out of the forks & get the valving modified at a decent suspension shop. I have personally managed to get a couple of my own bikes working well enough for me without going down that track. And I don't mind pushing them along a bit. If you get my drift.
    I have found that getting the front end working right will make the biggest differences in how hard your bike can be ridden. If the front end sticks then you can confidently carry plenty of corner speed.
    Unfortunately rear shocks with no damping adjustment cannot be tuned without open heart surgery. Most will have some sort of rebound adjustment though. As long as the sags are set right then one should be able to come up with a reasonable compromise.
    And that is the trick. You can never set up a bike to be perfect everywhere. Its always a compromise. There's always a bump somewhere bigger than what you have set up for. Or you run into a bumpy corner a bit quicker than you should have. Main thing is -have fun.
  4. There's alot of good info in all that :)
    so as a favour to Roarin and to exercise my 'mod' status ( which i rarely get to do in here :LOL: )
    I've promoted this to a Sticky so it wont get lost in the days/weeks to come.

    :twisted: :LOL: :p
  5. That was great Roarin. The lamen terms suited me perfectly.
  6. Oy Cathar, I was gonna put that link up!!! Good work Bro :)

    Here's another link to a bunch of setup articles. The suspension set up articles say much the same stuff as the sasbk site, but have more of the why. They were authored by Steve Brouggy - head honcho of Superbike school.

  7. Also heres a simple chart if anyone is interested.. :)

    • Like Like x 1
  8. Link doesn't wk
  9. How do you find someone to do this for you?
  10. where are you? many of the suspension specialists will set it up for you as will some mechanics. cost is reasonable from memory
  11. North east of Melbourne (Eltham) but willing to travel anywhere if people think there is a particular person I should be seeing
  12. To have it set up personally is about forty five minutes to an hours work work. If it's adjustable. Or what you will be charged at a decent shop.
    Some are getting so tech now you need a specialist suspension tuner with their high/low adjustment on both bump and bound lol
    For the road you want it to use all it's travel, so be as soft as you can stand it. Helps tyre life as well.
  13. Everyone who has seen the bike this weekend has questioned the suspension.

    If I now say I have no chicken strip on my front tire but have quite a lot on the rear does that make a difference to your opinion?
  14. Ha ..... wasn't making an opinion on ur bike..... girls pffhhht
    But what your describing does not sound good at all.
    If it's something like that the best was is to go back to factory spec's and work your way from there.
    Even if you use all your rear you should have 5mm at least of chooky bits on the front tyre. A noob more like 10mm.
  15. It is at factory specs. I bought it new and haven't changed anything. Probably just my shitty riding but everyone comments how soft the suspension is. I'd like to get it properly checked. Yeah... I am a girl...I cant "go from there", I need to pay someone to get "there"

  16. I would question what tyres you have on and what shape they are firstly, suspension second. But if everyone is saying it's to soft, then chances are everyone is making a good point.